1. Field of the Invention
The present invention is directed to a hair clipper, and more particularly to a powered hair clipper capable of varying a cut length of the hairs especially suitable for cutting the hairline at the nape.
2. Description of the Prior Art
Hair clippers with varying cut length capability have been known as disclosed in U.S. Pat. No. 2,726,447 in which one of cutter blades is driven by a motor to move back and forth in the edgewise direction while it is driven to reciprocate transversely for hair shearing between toothed edges of the cutter blades. Since the one of the cutter blades is driven by the motor to shift its position relative to the other cutter blade in synchronism with the hair shearing reciprocating movement of that blade, the cut length will be continuously varied during the hair shearing operation without causing any unexpected shifting of the one cutter blade relative to the other cutter blade which would otherwise result in uneven hair cutting. Nevertheless, it is sometimes required for more convenient hair cutting to adjust the cut length or depth manually and independently of the hair shearing reciprocating movement. To satisfy this requirement, it is contemplated to provide an adjustor handle on a hair clipper housing to be readily accessible by the hand of the user for varying the cut length. However, there is a certain limitation in this structure that the one cutter blade should have sufficient frictional engagement with the other cutter blade in order to avoid unexpected shifting of the one blade relative to the other blade. The result is that a relatively great operational force is required for the user to slide the handle and therefore the cutter blade against the frictional force when adjusting the cut length of the hairs. This is inconvenient and is therefore a cause of accumulating fatigue of the wrist and of the fingers when shearing the hairs while varying the cut length continuously and manually, for example, in cutting the hairline at the nape where the cut length is gradually varied without leaving any noticeable steps therein. Such fatigue will mount rapidly especially when cutting the hairs of plural persons successively, which eventually results in an undesired uneven cut.